The present disclosure relates generally to computer aided design and manufacturing (CAD/CAM) and, more particularly, to a method for virtual inspection of virtually machined parts.
In numerically controlled (NC) milling technology, a tool or cutter is directed through a set of pre-recorded sequential trajectories to fabricate a desired shape from raw stock. This technology is capable of producing free-formed, sculptured surfaces while maintaining tight milling error tolerances. Consequently, NC milling technology is widely used in the production of complicated, high-precision products such as molds, dies, aerospace parts, etc. These products, especially molds and dies, typically influence many other subsequent production processes. In order to improve the accuracy and reliability of NC milling, certain verification methods are used to check milling tool paths for potential problems such as milling error, collision, and improper machining parameters, among others. Analytical methods are implemented to graphically simulate the milling process off-line and, in some cases, verify milling error, tool assembly collision, and other machining parameters. Thus, NC programmers can visualize the shape of milled parts and understand potential problems in an efficient, less expensive, and more accurate way.
Direct solid modeling is one approach used in simulating the material removal process, implemented through direct Boolean difference operations between a solid model of the workpiece and solid models of swept volumes of the milling tool. The milling process may be realistically simulated, resulting in an explicit solid model of the milled workpiece that may be graphically presented and reviewed. Since the milled part is explicitly defined by a solid representation, a subsequent analysis and computation of milling error, volume removal rate, or milling dynamics can be readily performed.
In the real world, the inspection of a milled part may be accomplished with a coordinate measuring machine (CMM), in which a small probe or pointer is used to trace the three-dimensional surfaces of the part in order to measure the specific dimensions thereof. Since such an inspection process assists in decreasing time and expense in the actual manufacturing of parts, it is also desirable to have a similar process for the verification of a mathematical-based, virtual machining application as described above.